Public health should be proud of the fact that we are an evidence-based profession. We have brought both the ethos and the tools of evidence-based clinical practice to the NHS and the wider public sector. However, we should not lose sight of the fact that public health is both a science and an art; this requires us to bring judgment to bear alongside evidence.

There are plenty of reasons that can be deployed in order not to use evidence. Sometimes issues can be seen as “blindingly obvious”; I recently saw a video of Brian Cox using the fact that we can actually see cosmic background radiation to energetically (and using colourful language) rebut a claim that the Big Bang is just a theory and may not have happened: “YOU CAN JUST ****** SEE IT.” As a newly qualified doctor on my first surgical firm, I worked with the team that had led the development of highly selective vagotomy as a curative treatment for peptic ulcer. In addition to the small operative mortality, many of the patients were left with long-term side effects such as malabsorption or diarrhoea. If I had dared to suggest that peptic ulcer might be a consequence of infection and amenable to curative treatment with antibiotics I would have been ridiculed, or worse. And yet this was subsequently found to be true and most patients are now successfully treated by H.pylori eradication rather than surgical intervention. The lessons I draw for my public health practice is that we should beware of our hidden prejudices and the influence of received wisdom; we should always be willing to challenge our assumptions. Other, less noble reasons for ignoring evidence include laziness, incompetence, pressure of work, and vested interests in outcomes; all issues that we should recognise and guard against as part of the ethical management of our own work.

Sometimes the evidence is rock solid but it is still not used to drive population health. The classic example must be smoking; we have known about the link between smoking and lung cancer since the work of Doll and Hill in the 1950s. But it took until 2007 for smoke-free public places to be enshrined in legislation across the UK. The 10-year anniversary of this achievement is an opportunity to recognise and celebrate its impact but also to raise the important question about where accountability lies for the thousands of avoidable deaths that have resulted from the decades-long delay in effective action. The answer seems to be “nowhere”. It seems to me that there is a failure in public sector governance if there is no accountability for inaction in the face of convincing evidence. The horrific events at Grenfell Tower perhaps serve as a more recent example.

And, of course, the evidence base is never complete, and we are often faced with contradictory evidence that steers us towards different courses of action. The recent debate about regulation of electronic cigarettes is a useful example. Evidence of the benefits as a smoking cessation aid have to be balanced by currently unquantifiable risks including the direct and indirect effects of vaping, and the potential for a new generation of young people to become addicted to nicotine. When faced with these sorts of uncertainty we have several options. We can commission further research, but that takes time. We can use a trial and error approach, but that brings risk (think of the death and illness last year of fit young volunteers in pharmaceutical trials in France). We can use a risk management and mitigation approach – something we all do unthinkingly in our daily lives when we buckle our seatbelts. And we can use a precautionary approach but, if used inappropriately, this might stifle innovation and change that could have a positive impact on population health.

Our approach in Wales has been to follow the thread of evidence-based public health action, from our research and development commitments (£43m per year), through the programme of action for our government, the legislative framework of the Wellbeing of Future Generations Act which requires public bodies to plan and report on population health outcomes, then through to our recently passed Public Health Act which has incorporated health impact assessment into our policy and planning. In Wales, we believe that evidence matters, but judgment and compassion also need to factor into our decision-making.

By Dr Jennifer Mindell, Reader in Public Health, Research Department of Epidemiology and Public Health, University College London

The government is proposing to ban the sale of diesel and petrol vehicles from 2040, to address air pollution in the UK that regularly breaches health-based EU regulations.

There are three main ways to improve UK air quality: reducing emissions from vehicles; driving less; and dealing with other sources of air pollution. The government’s preferred approach seems to be ‘business as usual, but less pollution from existing travel patterns’. Yet, even with this route, they are not committing to a scrappage scheme for diesel. This would produce air-quality benefits in the short-term, instead of in the 2040s – or even the 2050s and 2060s, as some individuals and businesses keep their vehicles for a long time. A scrappage scheme needs to be available to all individuals and businesses, regardless of size, and needs to encompass vehicles of all ages. Although older vehicles are known to be very polluting, no-one really knows about new vehicles! This could be complemented by financial help for retrofitting, particularly for older buses and lorries, if replacement isn’t an option.

Drivers of diesel cars are understandably aggrieved. They were urged to buy diesel engines by previous governments and given financial incentives to do so, because of the lower CO2 emissions per km. The higher emissions of other pollutants were ignored. Those with newer vehicles have no idea what their car really emits, due to the scandalous behaviour of manufacturers. This is yet another parallel with the tobacco industry (1) which designed cigarettes to produce low tar and nicotine in the laboratory but not when used by actual smokers.

Chargeable clean-air zones (low or ultra-low emission zones) are, according to a technical report issued by the government earlier this year, the most effective mechanism, but we understand that the government’s strategy will restrict charging to the last, not the first, resort. This is one of the areas, along with improved infrastructure for transport options other than private car use, that local authorities can contribute to greatly, but they need adequate powers and adequate resources. As air pollution costs the country £20 billion annually (2), the proposed figure of £255million to local authorities is a drop in the ocean.

The government is apparently also going to urge local authorities to speed traffic flows, by amending traffic-light settings and removing speed humps. What is actually needed is more calming, not less, to support smoother driving. It is not speed humps but the marked acceleration and braking that many drivers do that increases pollution. Greater use and enforcement of, and adherence to, area-wide 20mph limits without traffic calming would be better still.

Lower speeds, which would also support more and more pleasant walking and cycling, bring me to the better approach. Instead of persuading (in the next two decades) or requiring (from 2040) people to replace their existing car with an electric car, the health gains would be far greater if people travelled by public transport, walked or cycled whenever possible. As well as reducing pollution and carbon emissions, this generally increases physical activity and can improve wellbeing and reduce obesity and its consequences.

Reductions in pollutant emissions can also be achieved by reducing the need to travel. If people who could do so worked at home once a week, that would reduce their commuting by 20%. Land-use planning that encourages mixed use can shorten journeys sufficiently to make non-car options more feasible, although this will take longer. But as the government proposal for banning sales of diesel and petrol cars is to start in 2040, they are talking longer term anyway.

The government also needs to acknowledge that, although mobile sources are the largest category of pollutants, they are not the only ones. Two major contributors are buildings, including both homes and businesses, and transboundary industrial pollution from mainland Europe. Ministerial engagement with European countries will be necessary to deal with the latter. Local authorities need to be given the powers to address the former.
Air pollution is a major contributor to health inequalities. Poorer people are more likely to be exposed to higher pollutant levels. They are also more susceptible to the harmful effects of pollutants as they are more likely to have circulatory diseases (particularly heart disease and strokes) and respiratory diseases, such as chronic bronchitis or emphysema (now called chronic obstructive pulmonary disease) or asthma. Improving air quality is an important factor in reducing health inequalities.

The other option that we trust the government won’t take is to move the goal posts when (or if?) the UK is no longer bound by EU legislation. That would really be a cynical approach to the population’s health.

Disclaimer

The aim of this blog is to encourage discussion and debate on public health issues. The views expressed here are the personal views of authors, and the content does not reflect the official position of the Faculty of Public Health. However, discussion generated here may be used to influence the development of organisational policy.